For purposes of clarity and consistency, the following terms as used throughout this text and the appended claims should be interpreted as follows:
The term “fluid” should be broadly interpreted as encompassing a liquid, a suspension of a granulate solid in a liquid, a gel, a foam, and a spray, for example.
The term “product” should be interpreted as encompassing soap (including shower gel), shampoo, disinfectant, detergent, moisturizer, hair conditioner, and exfoliating scrub, for example, including mixtures of these substances.
The “liquid product” may be dispensed directly through the outlet nozzle, or may first be mixed with another substance, such as air or another gas, or a granulate solid, for example.
The term “pump” refers to any type of pump suitable under the circumstances.
The pump in question may employ a piston, bellows, and/or membrane, for example. These points will be discussed in more detail below.
Fluid product dispensers of a type having a housing for accommodating an assembly, the assembly having a liquid reservoir for containing a liquid product, a pump, connectable to the reservoir, for dispensing the fluid product using the liquid product as an input, and an outlet nozzle, serving to convey and dispense the fluid product from the pump are known. In a typical example, the pump includes a liquid chamber, for containing a dose of the liquid product, obtainable from the liquid reservoir, and a pressurizing device, which allows liquid product to be drawn into or expelled from the liquid chamber. One example is described in U.S. Pat. No. 5,445,288 (Deb). Such dispensers are, for example, employed in washrooms, toilets, kitchens, hospitals, surgeries, hair/beauty salons, workshops and factories. In many cases, such dispensers are mounted to a wall, often in the vicinity of a basin, bath, shower or toilet bowl; alternatively, such dispensers may be free-standing, and may be placed on a shelf, worktop or wash hand basin, or a trolley. In use, the pressurizing device is typically operated by hand, arm or elbow (e.g., via a manual actuating organ, such as a lever or button) so as to dispense a quantity of fluid product. In many applications, this fluid product will be dispensed into the operator's hand, or onto a carrier such as a cloth, after which the fluid product is rubbed onto the skin, or is applied from said carrier onto a surface to be treated, such as a metal, ceramic or plastic surface to be cleaned and/or disinfected, for example. In practice, the liquid reservoir may be collapsible (e.g., in the form of a plastic pouch) or (quasi-) rigid (e.g., in the case of a bottle or tub). As an alternative to a manual actuating organ, an actuating organ employing an electric actuator is also possible; in this case, the electric actuator can be triggered by a signal from a detector that registers the presence of a member (such as a hand or cloth) onto which fluid is to be dispensed. This latter alternative is not disclosed in U.S. Pat. No. 5,445,288, but it relies on a generally known principle.
In the dispenser described in U.S. Pat. No. 5,445,288, the liquid chamber is accompanied by a co-operating (ancillary) air chamber, which is provided with its own (ancillary) pressurizing device (a piston arrangement in the case in hand). During a filling stroke, the respective pressurizing devices are used to “evacuate” the liquid and air chambers, thereby drawing a dose of liquid product into the liquid chamber from the attached liquid reservoir (through a hydraulic inlet valve), and drawing a dose of air into the air chamber (through a pneumatic inlet valve). During an ensuing dispensing stroke, the respective pressurizing devices are used to “compress” the liquid and air chambers, whence their doses of liquid product and air are simultaneously forced into the outlet nozzle, where they co-mingle in a turbulence-generating member (e.g., a sieve or mesh, a set of sieves/meshes, a porous plug, etc.) to produce foam, which is discharged through the outlet nozzle to the outside world.
In dispensers as set forth above, when the contents of the liquid reservoir are depleted, the whole assembly in the dispenser housing is replaced, i.e., the old liquid reservoir with attached (used) pump/nozzle is discarded, and a new liquid reservoir with attached (unused) pump/nozzle is mounted in the housing. This has been found to be necessary because, if only the liquid reservoir is replaced and the pump/nozzle is left in place, clogging of the dispenser can eventually occur. Conventionally, such clogging has been (primarily) attributed to oxidation of traces of liquid product that remain in the pump during its use over an extended period of time. So, although such regular replacement of the pump is a pity in terms of increased operational costs and environmental burden, it nevertheless is required in order to prevent malfunction of dispensers known from the prior-art.